This invention relates generally to an ultra-thin quartz crystal oscillator and in particular to a structural mode tuning fork quartz crystal vibrator wherein the tuning fork type quartz crystal vibrator is sandwiched between two cooperating case members with an external electrode wired through a through-hole or opening in the vibrator plate for providing two external electrodes on the same case member.
There is a pressing need for quartz crystal oscillators which are thin, small-size and can be produced at an overall low price. Such oscillators are required for making a thin electronic wristwatch which utilizes a quartz crystal oscillator as the time standard. In view of recent developments, the quartz crystal oscillator is the heart of these electronic wristwatches.
There are many proposals for providing thin, small-sized quartz crystal oscillators. Among these, the most attractive is the thin-plate tuning fork type quartz crystal vibrator including a frame integrally extending from the base of the tuning fork so as to surround the tine of the tuning fork. The vibrator is then sandwiched in between two opposed plates or box-shaped containers. This type of quartz crystal oscillator is worth considering in terms of its size and cost. However, there are serious shortcomings in using such a quartz crystal oscillator as it is expensive to produce due to special processing for conveniently providing the terminals in an easily accessible location for mounting the quartz crystal oscillator into the oscillator circuit. Accordingly, it is desirable to provide a thin-plate tuning fork type quartz crystal vibrator in a container which overcomes these disadvantages.